Conventionally, there is known a rotating electrical machine including a temperature detection device for detecting a temperature of an armature winding. In response to input of revolution speed information of a rotor, a protection temperature of the armature winding is calculated with the use of a map in which the protection temperature of the armature winding corresponding to the revolution speed of the rotor is set. The calculated protection temperature is compared to the temperature of the armature winding, thereby performing overheat protection of the armature winding (see, for example, Patent Literature 1).